Suction valve

ABSTRACT

A suction valve including a valve seat and a piston movably joined to the valve seat. The piston has a head for engaging the top surface of the valve seat and a stem extending downwardly from the head through the valve seat. A valve guide is positioned adjacent the bottom surface of the valve seat and slidably receives the stem. A valve keeper is fitted upon the stem such that the valve guide is disposed between the valve seat and the valve keeper. A keeper pin is slidably positioned within a transverse aperture in the stem and abuts the bottom of the valve keeper. A compressed spring is positioned between, and exerts opposing forces upon, the valve guide and the valve keeper so as to normally retain the head of the piston in engagement with the top surface of the valve seat.

FIELD OF THE INVENTION

The present invention relates generally to fluid handling apparatus and,more particularly, to direct response valves of reciprocating type.

BACKGROUND OF THE INVENTION

It is not uncommon for subterranean reservoir rocks to be fullysaturated with oil and gas yet be of such low permeability that they arenot feasible to develop in an economic manner. In such cases, productionrates are often boosted by resorting to hydraulic fracturing, atechnique that increases rock permeability by opening channels throughwhich reservoir fluids can flow to recovery wells. During hydraulicfracturing, a fluid such as water is pumped into the earth underextremely high pressure where it enters a reservoir rock and fracturesit. Sand grains, aluminum pellets, glass beads, or other proppants arecarried in suspension by the fluid into the fractures. When the pressureis released at the surface, the fractures partially close on theproppants, leaving channels for oil and gas to flow to recovery wells.

Specialized pumps are used to develop the pressures necessary tocomplete a hydraulic fracturing procedure or “frac job.” These pumps areusually provided with so-called fluid ends within which reciprocatingplungers place fluids under pressure. Suction and discharge valvescontrol fluid flow to and from the plungers. Improperly locating a valvein the fluid end at the time of manufacture can greatly weaken the fluidend, leading to catastrophic pump failures. Similarly, a valve that hastoo many projections can capture or “knock out” enough proppant to blockthe flow of fluid through a pump requiring, at a minimum, that time andeffort be invested to clear the blockage—costly undertaking in anoilfield environment.

SUMMARY OF THE INVENTION

In light of the problems associated with fluid ends of pumps used forhydraulic fracturing, it is a principal object of the invention toprovide a suction valve that reduces the likelihood of proppant beingknocked out of suspension to create a blockage. The suction valve of thepresent invention, thus, offers few impediments to flow through a fluidend when open so that fracturing fluids can flow smoothly through it. Asa result, fracturing fluids with higher than normal concentrations ofsuspended proppants can be pumped with substantial cost savings to theuser. Unlike a conventional, wing-guided valve, no spring retainerprojects into the plunger bore to close the open valve and, sometimes,undesirably knock out proppants.

It is another object of the invention to provide a suction valve of thetype described that may be seated in a relatively shallow pocket in afluid end. A valve pocket of shallow depth, of course, requires lessload-bearing material to be removed from the body of a fluid end thandoes one of greater depth like that required for a wing-guided valve. Itis less likely, then, that a fluid end configured to receive the suctionvalve of the present invention will fail from the development ofexcessive internal loads and stresses.

It is a further object of the invention to provide a suction valve ofthe type described that utilizes a valve seat that abuts its supportingsurface, i.e., a seat deck, at a shallow incline rather than at rightangles as has been commonly done. This slope of about 30° has been foundto significantly reduce zones of stress transmitted through a fluid end.It is along such zones that fluid ends have been known to crack and failunder load.

It is an object of the invention to provide improved elements andarrangements thereof in a suction valve for the purposes described whichis relatively lightweight in construction, inexpensive to manufacture,and dependable in use.

Briefly, the suction valve in accordance with this invention achievesthe intended objects by featuring a valve seat and a piston movablyjoined to the valve seat. The piston has a head for engaging the topsurface of the valve seat and a stem extending downwardly from the headthrough the valve seat. A streamlined valve guide is positioned adjacentthe bottom surface of the valve seat and slidably receives the stem. Avalve keeper is fitted upon the stem such that the valve guide isdisposed between the valve seat and the valve keeper. A keeper pin isslidably positioned within a transverse aperture in the stem and abutsthe bottom of the valve keeper. A compressed spring is positionedbetween, and exerts opposing forces upon, the valve guide and the valvekeeper so as to normally retain the head of the piston in engagementwith the top surface of the valve seat. Means are provided forpreventing the unintentional separation of the keeper pin from the stemand keeper.

The foregoing and other objects, features and advantages of the presentinvention will become readily apparent upon further review of thefollowing detailed description of the preferred embodiment asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more readily described with reference tothe accompanying drawings, in which:

FIG. 1 is a side elevational view of a suction valve in accordance withthe present invention with portions broken away to reveal detailsthereof.

FIG. 2 is a cross-sectional view taken along line 2—2 of FIG. 1.

Similar reference characters denote corresponding features consistentlythroughout the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the FIGS., a suction valve in accordance with thepresent invention is shown at 10. Valve 10 includes a valve seat 12 forpositioning in a suction passage 14 of a fluid end 16 and a piston 18for controlling the flow of fluid through passage 14. Piston 18 has ahead 20 for engaging the top surface 22 of seat 12 and a stem 24extending downwardly from head 20 through seat 12. The bottom of stem 24extends through a valve guide 26 positioned beneath valve seat 12. Avalve keeper 28 is fitted upon the bottom of stem 24 and is retainedthere by a keeper pin 30. A compressed spring 32 is positioned betweenguide 26 and keeper 28 to normally retain head 20 in engagement withseat 12 to prevent fluid flow through passage 14.

Valve seat 12 is a hollow cylinder or tube with top and bottom surfaces22 and 34 that are shaped to reduce turbulence. As shown, top surface 22is beveled such that it slopes downwardly and inwardly toward the centerof seat 12 at an angle of about 30°. Bottom surface 34, however, slopesupwardly and inwardly at an incline that increases evenly from the outerwall 36 of seat 12 to the inner wall 38 thereof. Thus, bottom surface 34is rounded.

Extending outwardly from the top of outer wall 36 of valve seat 12 is aperipheral flange 40. The bottom of flange 40 slopes downwardly andinwardly toward outer wall 36 at an angle of approximately 30°. Thisangle corresponds with that of a seat deck 42 in fluid end 16 thatsurrounds passage 14 thereby ensuring a strong platform for seat 12capable of reducing the transmission of stresses to fluid end 16. Toensure against fluid leaks around seat 12, outer wall 36 is providedwith a pair of peripheral grooves beneath flange 40 within which arepositioned O-ring seals 44 and 46 for engaging fluid end 16.

Head 20 of piston 18 has a beveled peripheral edge 48 that is adapted tosnugly engage top surface 22 of seat 12. Preferably, edge 48 carries adurable band or insert 50 formed of hard plastic that serves as sealingelement for valve 10. Insert 50 has a cross-section resembling aninverted “L” with an upper, horizontal leg 52 from which a vertical leg54 extends downwardly. A peripheral channel 56 with a corresponding,inverted “L” shape in head 20 receives and retains insert 50.

Valve guide 26 includes an inner ring 58 that slidably receives stem 24of piston 18. Ring 58 has an interior wall 60 for engaging stem 24 andan opposed exterior wall 62. Extending outwardly from the bottom ofexterior wall 62 is a radial flange 64 that serves as an abutment forthe top of spring 32. A top wall 66 connects walls 60 and 62 togetherabove flange 64 and slopes upwardly and inwardly so as to reduceturbulence in a fluid flowing through guide 26.

An outer ring 68 surrounds inner ring 58. Preferably, ring 68 has anoutside wall 70 for engaging fluid end 16 and an opposed inside wall 72.A circumferential flange 74 projects from outside wall 70 and, withoutside wall 70 and a topside wall 76 connecting walls 70 and 72,engages a seat deck 78 in fluid end 16 surrounding passage 14. Sinceguide 26 transmits significantly smaller loads to fluid end 16, it isnot necessary that seat deck 78 be sloped like seat deck 42.

Inner ring 58 and outer ring 68 are connected together by three,vertically oriented fins 82. Fins 82 radiate outwardly from exteriorwall 62 of ring 58 at 120° intervals to join with inside wall 72 of ring68. Fins 82 are, generally speaking, taller than they are wide to bestwithstand axial loads. Also, fins 82 slope upwardly from ring 58 to ring68 so that stem 24 may be supported at a point as far below top surface22 of seat 12 as practical to reduce the likelihood of piston wobble.Rings 58 and 68 and fins 82 being thin have been found to present suchminimal impediments to fluid flow through guide 26 that fluid endsequipped with valve 10 are capable of handling fluids with higherproppant concentrations than normal.

Valve keeper 28 is fitted over the bottom of stem 24 and has a conicalconfiguration. Thus, keeper 28 has an exterior diameter that increasesgradually from its top, where it has the same diameter of exterior wall62, to its bottom. Extending outwardly from the bottom of keeper 28 is aperipheral rim 84 that serves as an abutment for the bottom of spring32.

A recess 86 is provided in the bottom of keeper 28 for receiving keeperpin 30 extended through a transverse aperture 88 in stem 24. It shouldbe noted that the ends of recess 86 are closed to prevent pin 30 fromslipping from aperture 88. To further ensure that pin 30 does not becomeunintentionally disengaged from aperture 88, pin 30 is provided with aperipheral groove 90 at its midpoint and stem 24 is provided with atransverse bore 92 that intersects the bottom of aperture 88 at itsmidpoint and right angles. A roll pin 94 can be driven into bore 92 soas to pass through groove 90 and lock pin 30 in place in the manner of akey.

From the foregoing, it should be appreciated that use of valve 10 isstraightforward. After installation of valve 10 in fluid end 16, aplunger (not shown) is reciprocated above head 20. As the plunger movesforward to drive fluid from its cylinder, peripheral edge 48 of head 20is snugly pressed under the influence of spring 32 against top surface22 of seat 12 ensuring that no fluid leaks through passage 14. When theplunger travels back to its starting point, a partial vacuum is createdthat lifts piston 18 against the compressive force of spring 32 anddraws fluid upwardly through passage 14 and valve. The process ofopening and closing valve 10 is entirely automatic and requires merefractions of a second to accomplish. Since the valve 10 minimizesturbulent flow, there is little likelihood that proppant will becaptured by valve 10 to block flow through passage 14 under normalconditions of use. In fact, the resistance of valve 10 to knocking outproppant is so substantial that fluids containing greater proppant loadsthan those normally pumped can be delivered through valve 10 to providesubstantial time and cost savings to some users.

While the invention has been described with a high degree ofparticularity, it will be appreciated by those skilled in the art thatmodifications may be made thereto. Therefore, it is to be understoodthat the present invention is not limited to the sole embodimentdescribed above, but encompasses any and all embodiments within thescope of the following claims.

I claim:
 1. A suction valve, comprising: a valve seat being a tube withopen, top and bottom surfaces; a piston having a head for engaging saidtop surface of said valve seat and a stem extending downwardly from saidhead through said valve seat, said stem having a transverse aperture; avalve guide being positioned adjacent said bottom surface of said valveseat and slidably receiving said stem; a valve keeper being fitted uponsaid stem such that said valve guide is disposed between said valve seatand said valve keeper; a keeper pin slidably being positioned withinsaid transverse aperture and abutting the bottom of said valve keeper;and, a compressed spring positioned between, and exerting opposingforces upon, said valve guide and said valve keeper so as to normallyretain said head in engagement with said top surface of said valve seat.2. The suction valve according to claim 1 wherein said valve seatwherein said top surface is beveled to slope downwardly and inwardlytoward the center of said valve seat and said bottom surface slopesupwardly and inwardly at an evenly increasing incline so as to berounded.
 3. The suction valve according to claim 1 wherein said valveseat includes an outwardly extending peripheral flange, the bottom ofwhich slopes downwardly and inwardly.
 4. The suction valve according toclaim 1 wherein said piston further includes a plastic insert being aperipheral band having a inverted, L-shaped, cross section for engagingsaid top surface of said valve seat.
 5. The suction valve according toclaim 1 wherein said valve guide includes: an inner ring for slidablyreceiving said stem of said piston; an outer ring surrounding said innerring for engaging a supporting surface; a plurality of radially orientedfins connecting said inner ring and said outer ring together.
 6. Thesuction valve according to claim 5 wherein said inner ring includes: aninterior wall for engaging said stem of said piston; an exterior wallbeing opposite said interior wall; a radial flange extending outwardlyfrom said exterior wall serving as an abutment for the top of saidcompressed spring; and, a top wall being positioned above said radialflange and connecting said interior wall to said exterior wall, said topwall sloping upwardly and inwardly from said exterior wall to saidinterior wall.
 7. The suction valve according to claim 5 wherein saidouter ring includes: an outside wall for engaging a supporting surface;an inside wall opposite said outside wall; and, a circumferential flangeprojecting from said outside wall.
 8. The suction valve according toclaim 5 comprising three of said fins radiating from said inner ring at120° intervals, said fins sloping upwardly from said inner ring to saidouter ring.
 9. The suction valve according to claim 1 wherein saidkeeper is provided with a recess in its bottom for receiving said keeperpin and wherein said stem is provided with a transverse bore thatintersects the bottom of said transverse aperture and wherein saidkeeper pin is provided with a peripheral groove for alignment with saidtransverse bore and said suction valve further comprises a roll pin forsimultaneous positioning within said transverse bore and said peripheralgroove so as to lock said keeper pin in said transverse aperture.
 10. Asuction valve, comprising: a valve seat being a tube with open, top andbottom surfaces; a piston having a head for engaging said top surface ofsaid valve seat and a stem extending downwardly from said head throughsaid valve seat, said stem having a transverse aperture; a valve guidebeing positioned adjacent said bottom surface of said valve seat andslidably receiving said stem, said valve guide including: an inner ringfor slidably receiving said stem of said piston; an outer ringsurrounding said inner ring for engaging a supporting surface; and, aplurality of radially oriented fins connecting said inner ring and saidouter ring together, said fins sloping upwardly from said inner ring tosaid outer ring; a valve keeper being fitted upon said stem such thatsaid valve guide is disposed between said valve seat and said valvekeeper; a keeper pin slidably being positioned within said transverseaperture and abutting the bottom of said valve keeper; and, a compressedspring positioned between, and exerting opposing forces upon, said valveguide and said valve keeper so as to normally retain said head inengagement with said top surface of said valve seat.
 11. A suctionvalve, comprising: a valve seat being a tube with open, top and bottomsurfaces; a piston having a head for engaging said top surface of saidvalve seat and a stem extending downwardly from said head through saidvalve seat, said stem having a transverse aperture and a transverse borethat intersects the bottom of said transverse aperture; a valve guidebeing positioned adjacent said bottom surface of said valve seat andslidably receiving said stem, said valve guide including: an inner ringfor slidably receiving said stem of said piston; an outer ringsurrounding said inner ring for engaging a supporting surface; and, aplurality of radially oriented fins connecting said inner ring and saidouter ring together, said fins sloping upwardly from said inner ring tosaid outer ring; a valve keeper being fitted upon said stem such thatsaid valve guide is disposed between said valve seat and said valvekeeper; a keeper pin slidably being positioned within said transverseaperture and abutting the bottom of said valve keeper, said keeper pinhaving a peripheral groove adapted for alignment with said transversebore; a roll pin for simultaneous positioning within said transversebore and said peripheral groove so as to lock said keeper pin in saidtransverse aperture; and, a compressed spring positioned between, andexerting opposing forces upon, said valve guide and said valve keeper soas to normally retain said head in engagement with said top surface ofsaid valve seat.